CN104554265B - Vehicle braking/driving force control apparatus - Google Patents

Abstract

The present invention provides a brake-driving force control device for a vehicle, which prevents each wheel from reaching the limit of the drive force as much as possible when the vehicle motion is controlled by the brake-drive force of each wheel. In a vehicle in which the conversion rate of braking driving force into up-down force is greater for the rear wheels (10r) than for the front wheels (10f), the ECU (50) controls the yaw motion of the vehicle so that the When the driver requests that the brake driving force (F ^* ) be distributed to four wheels, the distribution ratio to the rear wheels (10r) is set to be larger than the distribution ratio to the front wheels (10f). Therefore, when the roll control required for the yaw motion control of the vehicle is performed, it is difficult to achieve the target braking driving force (Fx) of the front wheel on the turning outer side that requires the largest control driving force (Fcx). limit.

Description

Braking and driving force control device for vehicles

technical field

The present invention relates to a braking-driving force control device for a vehicle that independently controls the driving force and braking force of four wheels of the vehicle, namely front, rear, left, and right.

Background technique

Conventionally, there is known a vehicle brake-drive force control device that independently controls the drive force and brake force (both are collectively referred to as brake drive force) of the four wheels of the vehicle. For example, as one form of an electric vehicle, in a vehicle of an in-wheel motor type in which a motor is disposed inside or near a wheel and the motor is used to directly drive the wheel, the motor provided on each wheel can be independently controlled. Perform drive control. In a vehicle of the in-wheel motor system, by performing power running control or regenerative control on each electric motor, the driving torque or braking torque supplied to each wheel is individually controlled, thereby controlling vehicle travel and vehicle motion . For example, in the travel control device for a vehicle proposed in Patent Document 1, the yaw motion of the vehicle when turning is controlled, and the roll generated in accordance with the suspension characteristics of the vehicle as a result of the controlled yaw motion is controlled. The driving force of each in-wheel motor is controlled by suppressing the characteristic.

Patent Document 1: Japanese Patent Laid-Open No. 2009-143310

However, in the case of controlling the braking and driving force of the wheels to control the vehicle motion, there is a problem that the braking and driving force is biased towards the front wheel side or the rear wheel side so that a specific wheel reaches the output limit earlier than other wheels. The reason for this will be described below.

Each wheel is connected to the vehicle body via a suspension link mechanism. Generally, as shown in FIG. 3 , the instantaneous center of rotation Cf of the suspension link mechanism that connects the front wheels 10f and the body B is located behind and above the front wheels 10f, and the rear wheels 10r and the body B are connected to each other. The instantaneous center of rotation Cr of the linked suspension link mechanism is located in front and above the rear wheel 10r. Therefore, when the drive torque is supplied to the front wheels 10f, forward force Ff1 in the traveling direction of the vehicle acts on the ground contact point of the front wheels 10f, and this force Ff1 generates a force at the ground contact point of the front wheels 10f via the suspension connection. The vertical force Fzf1 exerted downward by the rod mechanism on the vehicle body B (vertical downward force acting on the suspension link mechanism). Therefore, by driving the front wheels 10f, a force in a direction to sink the vehicle body B acts. Conversely, when a braking torque is applied to the front wheels 10f, a rearward force Ff2 in the traveling direction of the vehicle acts on the ground contact point of the front wheels 10f, and by this force Ff2, a grounding force is generated at the ground contact point of the front wheels 10f via the suspension. The up-and-down force Fzf2 exerted upward by the link mechanism on the body B (the vertically upward component acting on the suspension link mechanism). Therefore, by braking the front wheels 10f, a force in a direction to float the vehicle body B acts.

On the other hand, with respect to the rear wheel 10r, the direction in which the vertical force is generated is opposite to that of the front wheel 10f. That is, when the driving torque is applied to the rear wheels 10r, forward force Fr1 in the traveling direction of the vehicle acts on the ground contact point of the rear wheels 10r, and this force Fr1 generates a force at the ground contact point of the rear wheels 10r via the suspension connection. The up-and-down force Fzr1 exerted upward by the rod mechanism on the body B (the vertically upward component acting on the suspension link mechanism). Therefore, by driving the rear wheels 10r, a force in a direction to float the vehicle body B acts. Conversely, when the braking torque is applied to the rear wheel 10r, a rearward force Fr2 in the traveling direction of the vehicle acts on the ground contact point of the rear wheel 10r, and by this force Fr2, a ground contact point of the rear wheel 10r is generated. The up-and-down force Fzr2 exerted downward by the link mechanism on the body B (the vertically downward component force acting on the suspension link mechanism). Therefore, by braking the rear wheels 10r, a force in a direction in which the vehicle body B sinks acts.

If the angle formed by the line connecting the ground contact point of the front wheel 10f and the instantaneous center of rotation Cf and the ground plane is θf, and the angle formed by the line connecting the ground contact point of the rear wheel 10r and the instantaneous center of rotation Cr is formed by the ground plane The angle of θr is set to θr, then for the front wheel 10f side, the magnitude of the up and down force is the value obtained by multiplying tan (θf) by the brake driving force Ff (Ff1 or Ff2), and for the rear wheel 10r side, The magnitude of the vertical force is a value obtained by multiplying tan (θr) by the braking driving force Fr (Fr1 or Fr2). This tan(θf) or tan(θr) is a conversion rate for converting the braking driving force into the vertical force of the vehicle body B. In a general vehicle, θr is larger than θf (θf<θr) depending on the structure of the suspension link mechanism. Therefore, regarding the conversion ratio, the suspension link mechanism of the front wheel 10f is smaller than the suspension link mechanism of the rear wheel 10r. Therefore, the control range of the braking driving force is the same on the front wheel 10f side and the rear wheel 10r side, but the control range of the vertical force is smaller on the front wheel 10f side than on the rear wheel 10r side. That is, the range of the up-and-down force that can be generated by the control of the braking-driving force of the front wheels 10f becomes narrower than the range of the vertical force that can be generated by the control of the braking-driving force of the rear wheels 10r.

Therefore, when it is necessary to ensure the driver's requested braking-driving force corresponding to the driver's operation amount and to generate vertical force to control the motion of the vehicle, the braking-driving force of the front wheels 10f tends to exceed the front wheel 10f initially. The control range (upper limit) of the inner motor. Thus, the control range of the vehicle motion control is narrowed.

This is also the same in a vehicle in which the suspension link mechanism of the rear wheel 10r has a smaller conversion rate of the braking driving force into the vertical force of the vehicle body than that of the suspension link mechanism of the front wheel 10f. Therefore, the braking-driving force of the rear wheel 10r tends to exceed the control range (upper limit) of the in-wheel motor initially.

Contents of the invention

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent each wheel from reaching the limit of the driving force as much as possible when performing vehicle motion control using the braking driving force of each wheel.

In order to achieve the above object, the present invention is characterized in that it is a braking and driving force control device for a vehicle, comprising: an actuator (30), which independently drives the front, rear, left, and right wheels, and can generate a representative driving force and a braking force at each wheel. The braking driving force of both sides of the power; the suspension linkage mechanism (20), which independently connects the front, rear, left, and right wheels with the vehicle body, and converts the braking driving force of the wheels driven by the actuator into the vehicle body The force in the up and down direction; the target braking and driving force calculation unit (50, S17), calculates the target braking and driving force of the four wheels, and the target braking and driving force includes the driver's request limit set based on the driver's operation amount. Dynamic driving force and braking driving force for motion control required for vehicle motion control; and actuator control unit (50, 35, S18), controlling the action of the actuator according to the target braking driving force, wherein, The suspension link mechanism is configured so that the conversion rate of the braking driving force into the force in the vertical direction of the vehicle body is different between the front wheel side and the rear wheel side, and the vehicle braking driving force control device An allocation setting unit (50, S15) is provided that sets the wheel connected to the suspension link mechanism on the side with the higher conversion rate than the wheel with the lower conversion rate. The distribution of the driver's requested braking and driving force to the front and rear wheels is set so that the wheel to which the suspension link mechanism on one side is connected is large.

In the present invention, the front, rear, left, and right wheels are connected to the vehicle body through suspension link mechanisms provided independently for the respective wheels. Each wheel is provided with driving force and braking force by an actuator. As the actuator, for example, an in-wheel electric motor built into a wheel of the wheel is used. The brake driving force of the wheel driven by the actuator is converted into a force in the vertical direction of the vehicle body by the suspension link mechanism. By controlling the force in the vertical direction, the motion of the vehicle can be controlled. For example, the roll state, the pitch state, and the heave state of the vehicle can be controlled. The target braking and driving force calculation unit calculates the target braking and driving forces of the four wheels. The target braking and driving forces include: the driver's request limit set based on the driver's operation amount, such as the accelerator operation amount and the brake operation amount. dynamic driving force; and braking driving force for motion control required for vehicle motion control. The actuator control unit controls the operation of the actuator according to the target braking driving force.

The suspension link mechanism is configured so that the conversion rate of the braking driving force into the force in the vertical direction of the vehicle body is different between the front wheel side and the rear wheel side. For example, when viewed from the side of the vehicle, the slew rate is a value corresponding to the magnitude of the angle formed by the line connecting the ground contact point of the wheel and the instantaneous center of rotation of the suspension linkage connecting the wheel and the ground contact horizontal plane. Therefore, it becomes such a structure that the angle formed by the line connecting the ground contact point of the front wheel and the instantaneous rotation center of the suspension link mechanism and the ground contact horizontal plane is the same as the angle between the ground contact point of the rear wheel and the instantaneous rotation center of the suspension link mechanism. The angles formed by the line of the center connection and the ground plane are different. Therefore, the range of the vertical force that can be generated by the control of the brake-driving force of the wheel is different between the front wheel and the rear wheel, and the wheel connected to the suspension link mechanism with the smaller conversion ratio is smaller. As a result, when the driver's required braking and driving force is to be ensured and the vertical force is generated to control the motion of the vehicle, the braking and driving force of the wheel connected to the suspension link mechanism on the side with a smaller conversion ratio tends to be preceded. The control range (actuation limit of the actuator, or the actuation limit determined by the friction of the road surface) is exceeded.

Therefore, in the present invention, the allocation setting means is configured such that the wheel connected to the suspension link mechanism on the side with a higher conversion rate is larger than the wheel connected to the suspension link mechanism on the side with a smaller conversion rate. Sets the distribution of the driver's requested brake-actuation force relative to the front and rear wheels. Therefore, in the wheel connected to the suspension link mechanism on the side with a smaller conversion rate, the braking driving force required by the driver can be satisfied, and the effective driving force range that can be used for vehicle motion control can be ensured. , so that the braking driving force is not easy to reach the driving force limit.

Another feature of the present invention is that the vehicle brake-driving force control device includes a distribution switching unit (50, S13, S14, S15), and the distribution switching unit operates in conjunction with When the vehicle motion control is not implemented, the driver's requested brake-driving force is switched over such that the distribution ratio of the driver's braking drive force to the wheels connected to the suspension link mechanism on the side with the higher conversion ratio is larger. The driver requests the distribution of braking and driving force to the front and rear wheels. At least in the case of implementing the vehicle motion control, the distribution setting unit is connected to the suspension link mechanism on the side where the conversion ratio is large. The distribution of the driver's requested braking-driving force to the front and rear wheels is set so that one of the wheels is larger than the wheel connected to the suspension link mechanism on the side with the lower conversion ratio (S15).

In the present invention, when the vehicle motion control is implemented, the allocation switching unit calculates the ratio of the driver's required brake driving force to the suspension link mechanism on the side with a larger conversion ratio than when the vehicle motion control is not implemented. When the distribution ratio of the connected wheels is large, the distribution of the driver's request brake driving force to the front and rear wheels is switched. In addition, at least when the vehicle motion control is performed, the allocation setting means connects one of the wheels connected to the suspension link mechanism with a higher conversion rate than the suspension link mechanism with a smaller conversion rate. The way the wheels are large sets the distribution of the driver's required brake-actuation force relative to the front and rear wheels. As a result, when the vehicle motion control is performed, the effective driving force range usable for the vehicle motion control can be ensured to a large extent among the wheels connected to the suspension link mechanism on the side with a smaller conversion ratio, Therefore, the braking driving force is less likely to reach the driving force limit.

Another feature of the present invention is that the vehicle brake-driving force control device includes a non-motion control allocation setting unit, and when the non-motion control allocation setting unit is not performing the vehicle motion control, The distribution of the driver's required braking and driving force to the front, rear, left, and right wheels is equalized (S14).

According to the present invention, when the vehicle motion control is not performed, since the force generated by the tires is equalized, the vehicle stability can be improved.

Another feature of the present invention is that the distribution switching unit requests the driver to brake and drive force in a case where the yaw motion control of the vehicle is implemented, compared with a case where the yaw motion control of the vehicle is not implemented. Switching the distribution of the driver's requested braking and driving force with respect to the front and rear wheels, at least when implementing the vehicle In the case of the yaw motion control, the allocation setting unit connects the wheel connected to the suspension link mechanism on the side with the higher conversion ratio to the suspension on the lower conversion ratio side. The distribution of the driver's requested braking and driving force to the front and rear wheels is set so that the wheels connected by the lever mechanism are large.

In the case of implementing the yaw motion control of the vehicle, antiphase braking driving force (driving force for the turning outer wheel and braking force for the turning inner wheel) is set on the left and right wheels as the braking driving force for motion control. Therefore, the vertical force acting on the vehicle body via the suspension link mechanism of the left front wheel and the vertical force acting on the vehicle body via the suspension link mechanism of the right front wheel become opposite to each other, and roll occurs on the front wheel side of the vehicle body. moment. In addition, the vertical force acting on the vehicle body via the suspension link mechanism of the left rear wheel and the vertical force acting on the vehicle body via the suspension link mechanism of the right rear wheel become opposite to each other, and roll occurs on the rear wheel side of the vehicle body. moment. In this case, the direction of the rolling moment is opposite to each other on the front wheel side and the rear wheel side, but the magnitude of the rolling moment is on the wheel side connected to the suspension link mechanism whose conversion rate of the vertical force is large. The party is big. In order to suppress the roll of the vehicle body generated by the yaw motion control, it is necessary to perform roll control so that the roll moment generated on the front wheel side and the roll moment generated on the rear wheel side are in balance. . In order to suppress the roll of the vehicle body, it is necessary to brake the driving force of the wheel connected to the suspension link mechanism on the side with a smaller conversion rate than the wheel connected to the suspension link mechanism on the side with a higher conversion rate. The driving force is large, but if so, the braking driving force for motion control required for the turning outside wheel on the side connected to the suspension link mechanism on the side with a small conversion ratio becomes large.

Even in this case, in the present invention, when the yaw motion control of the vehicle is implemented, the driver's required brake-driving force is converted to The distribution ratio of the wheels connected to the suspension link mechanism on the side with the larger ratio is larger, and the distribution of the driver's request braking drive force to the front and rear wheels is switched. In addition, at least when the yaw motion control of the vehicle is carried out, the distribution setting means connects the wheel connected to the suspension link mechanism with a higher conversion rate to the suspension with a lower conversion rate than the wheel connected to the suspension link mechanism with a lower conversion rate. The distribution of the driver's request braking drive force to the front and rear wheels is set so that the wheels connected by the lever mechanism are large. Therefore, in the wheel connected to the suspension link mechanism on the side with a smaller conversion ratio, a margin is ensured to provide the brake driving force for motion control for performing yaw motion control and roll control. As a result, the turning outer wheel coupled to the suspension link mechanism on the side with a smaller conversion ratio is less likely to reach the drive limit, and roll control during yaw motion control can be performed satisfactorily. In addition, when the yaw motion control is not performed, the distribution of the driver's required braking and driving force to the front, rear, left, and right wheels can be equalized, and since the forces generated by the tires are equalized, the vehicle stability can be improved.

Another feature of the present invention is that the target brake-driving force calculation unit, when performing the yaw motion control of the vehicle, makes the front wheel drive force generated by the front wheel during the yaw motion control The braking driving force for motion control of each wheel is calculated in such a manner that the rolling moment and the rear wheel rolling moment generated by the driving force of the rear wheels are balanced ( S16 ).

In a vehicle equipped with a suspension link mechanism with different conversion ratios of vertical forces on the front wheel side and the rear wheel side, when the yaw motion control of the vehicle is performed, the front wheel side generated by the driving force of the front wheels The rolling moment and the rear wheel rolling moment generated by the driving force of the rear wheels are different in magnitude even if their directions are opposite. Therefore, the target brake-driving force calculating means calculates the brake-drive force for motion control of each wheel so that the front wheel roll moment and the rear wheel roll moment are in balance. In this case, the distribution of the driver's required braking and driving force to the front and rear wheels is set as follows: the ratio of one side of the wheel connected to the suspension link mechanism on the side with a larger vertical force conversion ratio to the vertical ratio The wheel that the suspension link mechanism on the side where the conversion rate of the force is small is large. Therefore, the roll of the vehicle body can be well suppressed.

Another feature of the present invention is that the vehicle brake-driving force control device includes a surplus force equalization unit (S15) that enables the brake-drive force of the wheels to pass through the suspension The distribution ratio of the driver's requested braking-driving force to the front and rear wheels is set so that the excess force of the vertical force generated by the frame link mechanism on the vehicle body is equal to the front and rear wheels.

According to the present invention, the residual force equalizing means sets the driver so that the residual force of the force in the vertical direction that can be generated in the vehicle body via the suspension link mechanism by the brake driving force of the wheel is equal to the front wheel side and the rear wheel side. The distribution ratio of the required brake-driving force to the front and rear wheels. Therefore, when performing vehicle motion control, it is possible to perform more balanced distribution of braking and driving force to the front and rear wheels. Accordingly, it is possible to suppress the brake-driving force of a specific wheel from reaching the limit first.

Another feature of the present invention is that the vehicle brake-driving force control device includes a low-required brake-drive force distribution ratio setting unit (S15), and the low-request brake-drive force distribution ratio setting unit is When the driver’s required braking and driving force is less than a preset value, the driver’s required braking and driving force is only distributed to the suspension link mechanism connected to the side with the larger conversion rate. The way the wheels are set relative to the distribution ratio of the front and rear wheels.

When the driver's request for braking and driving force is smaller than a certain value, it is impossible to realize that the remaining force of the vertical force generated by the braking and driving force of the wheel through the suspension linkage mechanism in the vehicle body is equal to the front wheel side and the rear wheel side. Condition. Therefore, in the present invention, when the driver's required braking-driving force is less than a preset value, the distribution ratio setting unit distributes the driver's required braking-driving force only to The wheel that is connected to the suspension linkage on the side with a higher conversion rate. That is, the driver's requested braking-driving force is not distributed to the wheels connected to the suspension link mechanism on the side with a smaller conversion ratio. Accordingly, it is possible to appropriately distribute the driver's requested braking/driving force to the front and rear wheels when the driver's requested braking/driving force is low.

Another feature of the present invention is that the vehicle braking and driving force control device has a state quantity corresponding distribution ratio setting unit (S15), and the state quantity corresponding distribution ratio setting unit detects the motion state quantity of the vehicle and corresponds to A distribution ratio of the driver's required braking and driving force with respect to the front and rear wheels is set based on the motion state quantity. In this case, the state quantity-corresponding distribution ratio setting unit sets such that the distribution ratio of the driver's requested braking-driving force to the rear wheel side increases as the motion state quantity increases.

According to the present invention, since the distribution ratio of the driver's requested braking-driving force to the front and rear wheels can be appropriately set in accordance with the amount of motion state, it is possible to prevent the braking-driving force of a specific wheel from reaching the limit earlier.

In the above invention, in order to facilitate the understanding of the invention, the reference numerals used in the embodiment are added in parentheses to the structure of the invention corresponding to the embodiment. The embodiment specified by the above symbols.

Description of drawings

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a vehicle braking-driving force control device according to the present embodiment.

FIG. 2 is a flowchart showing a motor drive control routine.

FIG. 3 is a diagram showing the relationship between the control range of the braking driving force and the control range of the vertical force.

FIG. 4 is a diagram showing braking and driving forces on the front and rear wheels required to balance rolling moments.

FIG. 5 is a diagram showing driver-requested distributed driving force, control-purpose driving force, and target driving force on four wheels when the driver-requested driving force is equally distributed.

6 is a diagram showing the driver's requested driving force distribution, control driving force, and target driving force on the four wheels when a large amount of driver's requested driving force is distributed to the rear wheels.

FIG. 7 is a characteristic diagram of the driving force distribution coefficient α.

Fig. 8 is a characteristic diagram of the driving force for control during the yaw motion.

Label description

1: vehicle; 10fl, 10fr, 10rl, 10rr: wheels; 20fl, 20fr, 20rl, 20rr: suspension; 21fl, 21fr, 21rl, 21rr: linkage; 30fl, 30fr, 30rl, 30rr: electric motor; 40: operation State detection device; 45: motion state detection device; 50: electronic control unit (ECU); Cf, Cr: instantaneous rotation center; θf, θr: instantaneous rotation angle.

detailed description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a vehicle 1 equipped with a vehicle braking-driving force control device according to the present embodiment.

The vehicle 1 includes a left front wheel 10fl, a right front wheel 10fr, a left rear wheel 10rl, and a right rear wheel 10rr. The left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are suspended from the vehicle body B via independent suspensions 20fl, 20fr, 20rl, and 20rr, respectively.

The suspensions 20fl, 20fr, 20rl, 20rr are connection structures that connect the vehicle body B and the wheels 10fl, 10fr, 10rl, 10rr, and are composed of the following parts: a link mechanism 21fl, 21fr, 21rl, 21rr composed of a cantilever; Suspension springs 22fl, 22fr, 22rl, 22rr absorb vertical loads and shocks; and dampers 23fl, 23fr, 23rl, 23rr dampen sprung (body B) vibrations. The suspension link mechanism of the present invention is an element that determines the instantaneous center of rotation, and is an entire element that determines the unsprung motion. Therefore, it does not mean only the link mechanisms 21fl, 21fr, 21rl, and 21rr, but represents the In addition to the mechanisms 21fl, 21fr, 21rl, 21rr, the entirety of the suspensions 20fl, 20fr, 20rl, 20rr including the suspension springs 22fl, 22fr, 22rl, 22rr and the shock absorbers 23fl, 23fr, 23rl, 23rr. For the suspensions 20fl, 20fr, 20rl, and 20rr, known four-wheel independent suspension systems such as a strut suspension or a double wishbone suspension can be used.

Motors 30fl, 30fr, 30rl, and 30rr are built into the wheels of the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr. The electric motors 30fl, 30fr, 30rl, and 30rr are so-called in-wheel motors, and are arranged under the unsprung of the vehicle 1 together with the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr, respectively, and are capable of transmitting power. The way is connected with the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr. In this vehicle 1, by independently controlling the rotations of the electric motors 30fl, 30fr, 30rl, and 30rr, the rotations of the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr can be independently controlled. resulting driving and braking forces.

Hereinafter, each wheel 10fl, 10fr, 10rl, 10rr, suspension 20fl, 20fr, 20rl, 20rr, link mechanism 21fl, 21fr, 21rl, 21rr, suspension spring 22fl, 22fr, 22rl, 22rr, shock absorber 23fl, 23fr, 23rl, 23rr, electric motor 30fl, 30fr, 30rl, 30rr, unless any one of them is specified, they are referred to as wheel 10, suspension 20, link mechanism 21, suspension spring 22, damper Device 23, motor 30. In addition, when distinguishing and specifying the front wheels 10fl, 10fr and the rear wheels 10rl, 10rr among the wheels 10fl, 10fr, 10rl, 10rr, the front wheels 10fl, 10fr are called the front wheels 10f, and the rear wheels 10rl , 10rr is called rear wheel 10r. Similarly, the suspension 20, the link mechanism 21, the suspension spring 22, the shock absorber 23, and the electric motor 30 are also referred to as the front wheel suspension 20f and the front wheel link when specifying the components on the front wheel side. The mechanism 21f, the front wheel suspension spring 22f, the front wheel shock absorber 23f, and the front wheel motor 30f are called the rear wheel suspension 20r, the rear wheel link mechanism 21r, and the rear wheel when specifying the components on the rear wheel side. Wheel suspension spring 22r, rear wheel shock absorber 23r, rear wheel motor 30r.

As each motor 30, for example, a brushless motor is used. Each motor 30 is connected to a motor driver 35 . The motor driver 35 is, for example, an inverter, and four sets are provided corresponding to the motors 30 , converts the DC power supplied from the battery 60 into AC power, and supplies the AC power to each motor independently. 30. As a result, each electric motor 30 is driven and controlled to generate torque to provide driving force to each wheel 10 . In this way, the case where electric power is supplied to the electric motor 30 to generate drive torque is referred to as power running.

In addition, each electric motor 30 also functions as a generator, and can generate electricity by using the rotational energy of each wheel 10 , and can regenerate the generated electric power to the battery 60 via the motor driver 35 . The braking torque generated by the electric motor 30 provides braking force to the wheels 10 . In addition, although a brake device is provided on each wheel 10, since it is not directly related to the present invention, illustration and description are omitted.

The motor driver 35 is connected to an electronic control unit 50 . The electronic control unit 50 (hereinafter referred to as ECU 50 ) includes a microcomputer including a CPU, ROM, RAM, etc. as a main part, and executes various routines to independently control the operation of the motor 30 . The ECU 50 is configured to connect the operating state detecting device 40 and the motion state detecting device 45, and input the detection signals output from these detecting devices 40, 45. The operating state detecting device 40 detects that the driver operates to drive the vehicle The operating state of the vehicle, the motion state detecting device 45 detects the motion state of the vehicle.

The operating state detection device 40 is made up of the following components, etc.: an accelerator sensor, which detects the driver's accelerator operation amount according to the stepping amount (or angle or pressure, etc.) of the accelerator pedal; input amount (or angle or pressure, etc.) to detect the driver's brake operation amount; and a steering angle sensor that detects the driver's steering operation amount on the steering wheel. The motion state detection device 45 is formed by appropriately combining the following sensors: a vehicle speed sensor, which detects the running speed of the vehicle body B; a yaw rate sensor, which detects the yaw rate of the vehicle body B; Acceleration in the up-down direction of the vehicle body B (sprung) at the wheel position; a lateral acceleration sensor that detects the lateral acceleration in the left-right direction of the vehicle body B; a pitch rate sensor that detects the pitch rate of the vehicle body B; a roll rate sensor that detects the pitch rate of the vehicle body B The roll rate of the vehicle body B is detected; the stroke sensor detects the stroke amount of each suspension 20 ; and the unsprung acceleration sensor detects the vertical acceleration in the unsprung vertical direction of each wheel 10 . And, for the sensor value including the direction element, the direction is identified by its sign.

As shown in FIG. 3 , in a side view of the vehicle, the suspension 20 that suspends each wheel 10 is configured such that the instantaneous center of rotation Cf (the instantaneous center of the front wheel 10f with respect to the vehicle body B) of the front wheel suspension 20f is located at a lower position than the front wheel. The wheel 10f is positioned rearward and upward, and the instantaneous center of rotation Cr (instantaneous center of the rear wheel 10r relative to the vehicle body B) in the rear wheel suspension 20r is positioned forward and upward relative to the rear wheel 10r. Also, if the angle (the smaller angle) between the line connecting the ground contact point of the front wheel 10f and the instantaneous center of rotation Cf and the ground contact horizontal plane is θf, and the line connecting the ground contact point of the rear wheel 10r and the instantaneous rotation center Cf When the angle (the smaller angle) formed by the line of the center Cr and the ground plane is θr, there is a relationship that θr is larger than θf (θf<θr). Hereinafter, θf is referred to as an instantaneous rotation angle θf, and θr is referred to as an instantaneous rotation angle θr.

In the structure (geometry) of such suspension 20, as shown in FIG. By this force Ff1 , a vertical force Fzf1 (vertical downward force acting on the front suspension 20f ) is generated at the ground contact point of the front wheel 10f, which urges the vehicle body B downward via the front suspension 20f. Therefore, by driving the front wheels 10f, a force in a direction to sink the vehicle body B acts. Conversely, when the braking torque is applied to the front wheels 10f, a rearward force Ff2 in the direction of travel of the vehicle acts on the ground contact point of the front wheels 10f, and by this force Ff2, a ground contact point of the front wheels 10f is generated. The vertical force Fzf2 of the suspension 20f urging the vehicle body B upward (the vertically upward component acting on the front suspension 20f). Therefore, by braking the front wheels 10f, a force in a direction to float the vehicle body B acts. In addition, when driving torque is supplied to the rear wheels 10r, forward force Fr1 in the traveling direction of the vehicle acts on the ground contact point of the rear wheels 10r, and this force Fr1 generates a force at the ground contact point of the rear wheels 10r via the rear wheel suspension. The vertical force Fzr1 (the vertically upward component acting on the rear wheel suspension 20r) exerts an upward force on the vehicle body B by the frame 20r. Therefore, by driving the rear wheels 10r, a force in a direction to float the vehicle body B acts. Conversely, when the braking torque is applied to the rear wheel 10r, a rearward force Fr2 in the direction of travel of the vehicle acts on the ground contact point of the rear wheel 10r, and a force Fr2 is generated at the ground contact point of the rear wheel 10r via the rear wheel. The vertical force Fzr2 exerted downward by the suspension 20r on the vehicle body B (vertical downward force acting on the rear suspension 20r). Therefore, by braking the rear wheels 10r, a force in a direction in which the vehicle body B sinks acts. In this way, the suspension 20 converts the driving force and the braking force of the wheel 10 into a force in the vertical direction of the vehicle body B. As shown in FIG.

Therefore, by controlling the driving force or braking force of the wheels 10, a force in the vertical direction can be applied to the vehicle body B, thereby enabling control of the motion state of the vehicle. Hereinafter, unless it is necessary to distinguish the driving force and the braking force, both are referred to as driving force. Just treat the braking force as a negative driving force. In addition, in the case of discussing magnitudes related to driving force and braking force, absolute values thereof are indicated.

The ECU 50 calculates the driver's required brake driving force (hereinafter referred to as the driver's required driving force F ^* ) based on the accelerator operation amount and the brake operation amount detected by the operation state detection device 40, The motion state of the vehicle detected by the device 45 is used to calculate the braking driving force for motion control (hereinafter referred to as the driving force for control Fcx) independently for each of the four wheels. Then, the total value of the driver's required distribution driving force Fdx and the control driving force Fcx is set as a target braking driving force (hereinafter referred to as a target driving force Fx) of each wheel 10. Fdx is the driving force obtained by distributing the driver's requested driving force F ^* to the four wheels. ECU 50 controls motor driver 35 to generate output torque corresponding to target driving force Fx by each motor 30 .

For the front wheel 10f side, the magnitude of the vertical force acting on the body B is the value obtained by multiplying tan(θf) by the driving force Ff (Ff1 or Ff2), and for the rear wheel 10r side, the magnitude of the vertical force acting on the body B is The magnitude of the vertical force is the value obtained by multiplying tan (θr) by the driving force Fr (Fr1 or Fr2). These tan(θf) and tan(θr) indicate the conversion rate of the driving force into the force in the vertical direction of the vehicle body B. FIG. The control range of the driving force of the front wheels 10f is the same as the control range of the driving force of the rear wheels 10r, but since the instantaneous rotation angle θf of the front wheel suspension 20f is smaller than the instantaneous rotation angle θr of the rear wheel suspension 20r, it is possible to The range of the up-and-down force generated by the control of the driving force of the front wheels 10f becomes narrower than the range of the up-and-down force that can be generated by the control of the driving force of the rear wheels 10r. Therefore, when the motion control of the vehicle is performed by generating a vertical force, the driving force of the front wheels 10f tends to exceed the control range (upper limit) initially. That is, the driving force of the front wheels 10f may exceed the control range (upper limit) in a state where the driving force of the rear wheels 10r still has a surplus.

For example, as shown in FIG. 5 , consider a case where the motor 30 is driven to perform a yaw motion of the vehicle when turning right. In the case of yaw motion, a control driving force Fcx in the forward direction is given to the turning outer wheel, and a control driving force Fcx of the same magnitude as the control driving force Fcx on the turning outer wheel but in the opposite direction is given to the turning inner wheel. . At this time, since the vertical force generated on the vehicle body B differs from left to right, roll moments Mxf, Mxr act as shown in FIG. 4 . The direction of the front wheel roll moment Mxf generated by the drive force Ff1 of the front wheels 10f is opposite to the direction of the rear wheel roll moment Mxr generated by the drive force Fr1 of the rear wheels 10r. In this case, if the driving force of the same magnitude is generated in the front wheel 10f and the rear wheel 10r, the magnitude of the vertical force (upward) generated by the driving force Fr1 of the rear wheel 10r becomes larger than that of the driving force of the front wheel 10f. The magnitude of the vertical force (downward) generated by Ff1 is large. Therefore, the rear wheel roll moment Mxr becomes larger than the front wheel roll moment Mxf. Therefore, it is necessary to balance the front wheel roll moment Mxf and the rear wheel roll moment Mxr. As shown in FIG. That is, in order to make the vertical force Fzf1 generated by the driving force Ff1 of the front wheels 10f and the vertical force Fzr1 generated by the driving force Fr1 of the rear wheels 10r have the same magnitude, it is necessary to make the driving force Ff1 of the front wheels 10f larger than that of the rear wheels 10f. The driving force Fr1 of the wheel 10r.

The target drive force Fx of the electric motor 30 of each wheel 10 is set as the total value of the driver's requested distribution drive force Fdx and the control drive force Fcx for vehicle motion control. Conventionally, the driver's requested distributed driving force Fdx is set to a value obtained by equally distributing the driver's requested driving force F ^* set according to the driver's operation amount to four wheels (F ^* /4). Therefore, for example, when the roll control is performed so that the front wheel roll moment Mxf and the rear wheel roll moment Mxr are balanced (equal) as described above during the yaw motion of the vehicle, as shown in FIG. 5 As shown, the control driving force Fcx of the front wheels 10f becomes larger than the control driving force Fcx of the rear wheels. As a result, the target driving force Fx of the front wheel 10fl, which is the turning outside front wheel, exceeds the control range (upper limit) of the electric motor 30 at first.

Therefore, in the present embodiment, by equalizing the distribution of the driving force to the front and rear wheels, it is difficult for the target driving force Fx of each wheel to reach the upper limit of the control range of the electric motor 30 .

FIG. 2 shows a motor drive control routine for solving such a problem. The ECU 50 repeatedly executes the motor drive control routine in a predetermined short cycle. When this routine is started, the ECU 50 first detects the driver's operation state and the vehicle motion state in step S11. In this case, the ECU 50 acquires the accelerator operation amount, the brake operation amount, and the steering operation amount obtained from the sensor values of the operation state detection device 40 , and acquires the values obtained from the sensor values detected by the motion state detection device 45 . The motion state quantity representing the speed of the vehicle and the degree of motion state (yaw motion, roll motion, pitch motion, heave motion) of the vehicle body.

Next, the ECU 50 calculates the driver's requested drive force F ^* based on the accelerator operation amount and the brake operation amount in step S12. The driver's requested driving force F ^* is a driving force in the front and rear directions of the vehicle that is required by the driver and should be generated in the entire vehicle, that is, a driving force for traveling. The ECU 50 stores relational data such as a map for deriving the driver's requested driving force F ^* from the accelerator operation amount and the brake operation amount, and calculates the driver's requested driving force F ^* using the related data.

Next, the ECU 50 judges in step S13 whether or not the switching condition for switching the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels is satisfied. The driver requests that the driving force F ^* be distributed to the four wheels. The right wheels 10fr, 10rr and the left wheels 10fl, 10rl are always equally distributed (1:1). However, the distribution of the front wheels 10f to the rear wheels 10r , to switch according to whether the switching condition is established.

In the present embodiment, the switching condition is satisfied when vehicle motion control including yaw motion control is required, and is not satisfied when yaw motion control is not required. For example, when the deviation between the ideal yaw rate set based on the steering angle and vehicle speed and the actual yaw rate detected by the yaw rate sensor exceeds an allowable value, the switching condition is satisfied, and when the deviation does not exceed an allowable value, the switching condition is not satisfied. Therefore, the switching condition is satisfied when a steering operation is detected, or when a yaw motion is detected due to disturbance although no steering operation is performed (the steering wheel remains neutral), or the like.

When the switching condition is not satisfied (S13: No), the ECU 50 sets the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels equally in step S14. That is, the driver's requested drive force F ^* is equally distributed to the four wheels 10 . On the other hand, when the switching condition is satisfied (S13: YES), in step S15, the driving force distribution coefficient α of the front and rear wheels is calculated. Here, the driving force distribution coefficient α represents a ratio of distributing the driver's requested driving force F ^* to the front wheels 10f. Therefore, the ratio distributed to the rear wheels 10r is represented by (1-α). The driving force distribution coefficient α calculated in this step S15 is set so that the driver requested driving force F ^* is distributed more to the rear wheels 10r than to the front wheels 10f.

The calculation of the driving force distribution coefficient α between the front and rear wheels will be described below. In this embodiment, the distribution ratio of the driver's required driving force F ^* to the front and rear wheels is set so that the remaining force in the vertical direction that can be generated in the vehicle body B via the suspension 20 by the driving force of the wheels 10 is The front wheel 10f side and the rear wheel 10r side are equal.

1. Up and down force

Assuming that the driving force of the front wheels 10f is Ff and the driving force of the rear wheels 10r is Fr, the vertical force Fzf generated by the driving force Ff of the front wheels 10f and the driving force Fr of the rear wheels 10r are The generated vertical force Fzr can be represented by the following equation.

Fzf=Ff×tanθf=Ff·Θf (defined as Θf=tanθf)

Fzr=Fr×tanθr=Fr·Θr (defined as Θr=tanθr)

2. The driving force of the front and rear wheels after distribution

If the driving force distribution coefficient α is set such that the driver required driving force F ^* is 2×Fd and the driving force distribution ratio of the front wheels 10f is α (0≤α≤1), the driving force distribution of the rear wheels 10r is The ratio becomes (1-α). The driving force Ff of the front wheels 10f and the driving force Fr of the rear wheels 10r can be represented by the following equation using the driving force distribution coefficient α.

Ff=α×2×Fd=2α·Fd

Fr=(1-α)×2×Fd=2(1-α)·Fd

When α=0, the driver requests that 100% of the driving force F ^* be distributed to the rear wheels 10r, and when α=1, the driver requests that 100% of the driving force F ^* be distributed to the front wheels 10f.

3. Up and down force after distribution

The vertical force Fzf generated by the driving force Ff of the front wheel 10f and the vertical force Fzr generated by the driving force Fr of the rear wheel 10r after the driver's requested driving force F ^* is distributed to the front and rear wheels can be expressed as follows express.

Fzf=Ff×Θf=2α·Fd·Θf

Fzr=Fr×Θr=2(1-α)·Fd·Θr

4. Maximum up and down force

If the maximum driving force that can be generated by the front wheel 10f and the rear wheel 10r is Fmax, the maximum vertical force Fzfmax that can be generated by the driving force Ff of the front wheel 10f and the maximum vertical force Fzfmax that can be generated by the driving force Fr of the rear wheel 10r can be The generated maximum vertical force Fzrmax can be represented by the following equation.

Fzfmax＝Fmax·Θf

Fzrmax＝Fmax·Θr

5. Remaining power of up and down force

If the remaining vertical force generated by the driving force Ff of the front wheel 10f is Fzfc (referred to as the remaining vertical force Fzfc on the front wheel side), and the vertical force generated by the driving force Fr of the rear wheel 10r is expressed as If the surplus force is Fzrc (referred to as rear wheel side vertical force surplus force Fzrc), the front wheel side vertical force surplus force Fzfc and the rear wheel side vertical force surplus force Fzrc can be expressed as follows.

Fzfc=Fzfmax-Fzf=Fmax·Θf-2α·Fd·Θf

=(Fmax-2α·Fd)·Θf

Fzrc=Fzrmax-Fzr=Fmax·Θr-2(1-α)·Fd·Θr

=(Fmax-2(1-α)·Fd)·Θr

6. Equalization of residual force of upper and lower forces

If the front wheel side vertical force residual force Fzfc is equal to the rear wheel side vertical force residual force Fzrc, the driver's demanded driving force can be distributed in a well-balanced manner, and it is possible to suppress that only a specific wheel reaches the driving limit first. In this case, the driving force distribution coefficient α can be set as follows.

Fzfc=Fzrc

(Fmax-2α·Fd)·Θf=(Fmax-2(1-α·Fd)·Θr

(1-2α·Fd/Fmax)=(1-2(1-α)·Fd/Fmax)·Θr/Θf

Here, if Fd/Fmax=A and Θr/Θf=D, it can be expressed as the following formula.

(1-2α·A)=(1-2(1-α)·A)·D

A is referred to as a maximum output ratio (0≤A≤1), and D is referred to as a front-to-back vertical force conversion ratio (D>1).

A is a value proportional to the driving force requested by the driver. In this case, A can use the throttle opening.

Here, when the driving force distribution coefficient α is solved, it can be expressed as the following equation.

1-2α·A＝D-2A·D+2α·A·D

2α·A(1+D)＝1-D+2A·D

α＝(1-D+2A·D)/2A(1+D))

7. Investigation of driving force distribution coefficient α

The case of A=0

The driving force distribution coefficient α can be represented by the following equation.

α＝((1-D)/A+2D)/2(1+D))

Since the front-back vertical force conversion ratio D becomes a value greater than 1, (1-D) becomes a negative value, and therefore, the driving force distribution coefficient α becomes a negative infinite value (α=−∞).

The available range of the driving force distribution coefficient α is 0 to 1 (0≦α≦1), therefore, the driving force distribution coefficient α should be set to zero (α=0).

The case of A=1

Substituting A=1 into the above formula, the driving force distribution coefficient α becomes 0.5 (α=0.5).

Here, A where α=0 is obtained.

0＝1-D+2A·D

A＝(D-1)/(2D)

Therefore, as shown in FIG. 7, when A is less than (D-1)/(2D), the driving force distribution coefficient α is set to zero, and when A is more than (D-1)/(2D) Here, the driving force distribution coefficient α is set to (1-D+2A·D)/(2A(1+D)).

Therefore, in step S15, when the maximum output ratio A determined by the driver's requested driving force F ^* (or the accelerator operation amount) is less than (D-1)/(2D), the ECU 50 sets the driving force distribution coefficient α to is set to zero, and when the maximum output ratio A is (D-1)/(2D) or more, the ECU 50 sets the driving force distribution coefficient α to (1-D+2A·D)/(2A(1+D )).

If the ECU 50 sets the driving force distribution coefficient α in step S14 or step S15, the process is performed in step S16. In step S16, the ECU 50 calculates the control driving force Fcx of each wheel 10, that is, the control driving force Fcfl of the left front wheel 10fl, the control driving force Fcfr of the right front wheel 10fr, and the control driving force Fcrl of the left rear wheel 10rl. , the driving force Fcrr for control of the right rear wheel 10rr. In addition, the driving force for control Fcx is a generic term for the driving forces for control Fcfl, Fcfr, Fcrl, and Fcrr. When the deviation between the ideal yaw rate and the actual yaw rate detected by the yaw rate sensor exceeds the allowable value, or at least one of the roll state quantity, the pitch state quantity, and the heave state quantity exceeds the allowable value In the case of, etc., the vehicle motion control is performed. Therefore, the processing of step S16 is skipped in the case where it is not necessary to perform vehicle motion control.

For example, the driving force Fcx for control of each wheel 10 is calculated using the following value: the target roll moment Mx for suppressing the roll motion of the vehicle body around the front-rear direction axis (roll axis) passing through the center of gravity Cg of the vehicle ; target pitching moment My, which is used to suppress the pitching motion of the vehicle body around the left-right direction axis (pitch axis) passing through the center of gravity Cg of the vehicle; target yaw moment Mz, which makes the vehicle around the vertical direction axis passing through the center of gravity Cg of the vehicle (yaw axis) turning; and a target heave force Fz for suppressing the up and down motion of the vehicle at the position of the center of gravity Cg, that is, heave motion (jumping). For calculation of these target values, various known calculation methods can be employed. For example, the ECU 50 detects the vertical position, velocity, and acceleration at the positions of the four wheels based on the sensor values detected by the stroke sensor and the sprung vertical acceleration sensor, and detects the roll state amount, the pitch state amount, and the heave state. , and calculate the target roll moment Mx, target pitch moment My, and target heave force Fz that have a predetermined relationship with these state quantities in advance. In addition, the ECU 50 calculates a target yaw moment set to eliminate the deviation based on the deviation between the ideal yaw rate set based on the steering angle and the vehicle speed and the actual yaw rate detected by the yaw rate sensor. Mz.

The ECU 50 calculates control driving forces Fcfl, Fcfr, Fcrl, and Fcrr, for example, according to the following equations.

【Equation 1】

Here, tf represents the track width (tread width) of the left and right front wheels 10f, and tr represents the track width of the left and right rear wheels 10r. Lf represents the longitudinal horizontal distance between the center of gravity Cg of the vehicle and the centers of the left and right front wheels 10f, and Lr represents the longitudinal horizontal distance between the center of gravity Cg of the vehicle and the centers of the left and right rear wheels 10r.

In this case, the ECU 50 selects three of the target roll moment Mx, target pitch moment My, target yaw moment Mz, and target heave force Fz to calculate control drive forces Fcfl, Fcfr, Fcrl, and Fcrr. This is because the driving force finally generated on each wheel 10 is determined by the driver's requested driving force F ^* , that is, there is a constraint that the total value of the control driving forces Fcfl, Fcfr, Fcrl, and Fcrr is set to zero. Therefore, calculations cannot be performed using 4 target values at the same time. In this case, when yaw motion control is required, the ECU 50 preferentially selects the target yaw moment Mz and the target roll moment Mx, and uses these two target values Mz, Mx, and the remaining target pitch moment My Calculate with any target value in the target heave force Fz.

In the case of controlling the yaw motion, since the front wheel roll moment Mxf and the rear wheel roll moment Mxr of different magnitudes are generated in directions opposite to each other as described above, it is implemented so that the front wheel The roll control is performed in such a manner that the roll moment Mxf and the rear wheel roll moment Mxr are balanced. In this case, since the conversion rate (tan(θf)) of converting the driving force of the front wheel 10f into the vertical force is smaller than the conversion rate (tan(θr)) of converting the driving force of the rear wheel 10r into the vertical force, Therefore, when the roll control is performed simultaneously with the yaw motion control, as shown in FIG. way to perform operations (comparing absolute values).

Next, in step S17, the ECU 50 calculates the final target driving force Fx of each wheel 10 according to the following equation, that is, the target driving force Ffl of the left front wheel 10fl, the target driving force Ffr of the right front wheel 10fr, and the target driving force Fx of the left rear wheel 10rl. The driving force Frl and the target driving force Frr of the right rear wheel 10rr.

Ffl=Fd·α+Fcfl

Ffr=Fd·α+Fcfr

Frl＝Fd·(1-α)+Fcrl

Frr＝Fd·(1-α)+Fcrr

Also, the target driving force Fx is a generic term for the target driving forces Ffl, Ffr, Frl, and Frr.

Next, the ECU 50 converts the target drive force Fx into a target motor torque Tx for driving the motor 30 in step S18 , and outputs a drive command signal corresponding to the target motor torque Tx to the motor driver 35 . When the target motor torque Tx represents the drive torque, current flows from the motor driver 35 to the motor 30 . When the target motor torque Tx represents the braking torque, current flows from the electric motor 30 to the accumulator 60 via the motor driver 35 . In this way, the electric motor 30 is subjected to power running control or regenerative control, and generates the target driving force Fx at each wheel 10 .

When the drive command signal is output to the motor driver 35, the ECU 50 temporarily ends the motor drive control routine. And, the motor drive control routine is repeatedly executed in a predetermined short cycle.

According to this motor drive control routine, when the yawing motion is controlled using the drive force of the motor 30, the driver's requested drive force F ^* is more distributed to the rear wheels 10r than to the front wheels 10f. Therefore, even if the roll control is performed so that the roll moment generated on the front wheel 10f side and the roll moment generated on the rear wheel 10r side are balanced, as shown in FIG. The target driving force Fx (=Ffl) of the front wheels 10fl. That is, since the driver's requested distributed drive force Fdx (=Fd·α) of the front wheels 10fl is made smaller than the driver's requested distributed drive force Fdx (=Fd·(1−α)) of the rear wheels 10rl, it is possible to provide The control driving force Fcx of the front wheels 10f has a large margin, and the target driving force Fx of the front wheels 10fl does not easily reach the output limit even if the roll control is performed simultaneously with the yaw motion control. Therefore, the roll control performed during the yaw motion control can be satisfactorily performed.

In addition, when the yaw motion control is not performed, the distribution of the driver's requested driving force F ^* to the front, rear, left, and right wheels is set to be equal. This equalizes the forces generated by the tires, so that vehicle stability can be improved.

In addition, the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels is set so that the surplus force of the vertical force that can be generated in the vehicle body B by the driving force of the wheels 10 is equal to the front wheel 10f side and the rear wheel 10r side. . Therefore, it is possible to distribute the driving force to the front and rear wheels in a more balanced manner. Accordingly, it is possible to more favorably suppress that the driving force of a specific wheel 10 reaches the limit earlier. In addition, when the driver's requested driving force F ^* is smaller than a predetermined setting value, the driver's requested driving force F ^* is distributed only to the rear wheels 10r. Accordingly, it is possible to appropriately distribute the driving force to the front and rear wheels when the driver's demand for driving force is low.

The vehicle braking-driving force control device according to the present embodiment has been described above, but the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the purpose of the present invention.

(Modified example of assignment switching condition)

For example, in the present embodiment, on condition that vehicle motion control including yaw motion control is performed, the driver requested driving force F ^* is switched from equal distribution to front and rear wheels to distribution biased to rear wheels (S13). This is because, in the case of the yawing motion control, it is possible to set the distribution of the driving force for control to different values for the front and rear wheels, which is particularly effective. However, the present invention is not limited to this, and may not be limited to yaw motion control, but may switch the driver's requested driving force F ^* from equal distribution to front and rear wheels to distribution biased to rear wheels on the condition that vehicle motion control is performed. For example, it is also possible to detect at least one motion state quantity among the rolling motion amount (rolling moment, etc.), vertical motion amount (up and down force, etc.), pitching motion amount (pitching moment, etc.) of the vehicle, and when the detected motion state amount If the value exceeds the set value (allowable value), the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels is switched in step S13. Also in this case, it is possible to prevent the front wheel motor 30f from reaching the output limit first, and to generate a large vertical force on the front wheel 10f side.

In addition, in this embodiment, when the distribution switching condition is satisfied, the driver's requested driving force F ^* is switched from an equal distribution to the front and rear wheels to a distribution biased to the rear wheels. The distribution ratio of the driver's request driving force F ^* to the rear wheels 10r is set to be larger than that of the front wheels 10f.

(Modification of distribution ratio)

In the present embodiment, the driver's required driving force F ^* is set with respect to the front and rear wheels so that the remaining force of the vertical force that can be generated in the vehicle body B by the driving force of the wheels 10 is equal to the front wheel 10f side and the rear wheel 10r side. distribution ratio (S15). However, the present invention is not limited thereto. For example, when the switching condition is satisfied, in step S15, the distribution ratio of the driver's requested driving force F ^* to the rear wheels may be switched to a constant value greater than that of the front wheels. Compare.

Alternatively, a yaw moment generated in the vehicle may be detected, and a distribution ratio of the driver's requested driving force F ^* to the front and rear wheels may be set based on the yaw moment. For example, in step S11, the amount of yaw motion (yaw moment, etc.) of the vehicle may be detected, and in step S15, the driver's requested drive force F ^* relative to the front and rear wheels may be set in accordance with the magnitude of the detected amount of yaw motion. distribution ratio. In this case, it may be set such that the distribution ratio to the rear wheels 10 r increases stepwise or continuously as the detected yaw motion amount increases. Accordingly, as the amount of yaw motion increases, the surplus force of the vertical force of the front wheels 10f increases, and roll control accompanying the yaw motion can be appropriately performed.

In addition, not limited to the amount of yaw motion, the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels may be set according to the magnitude of the motion state amount. For example, it is also possible to detect at least one motion state quantity in the amount of rolling motion (rolling moment, etc.), the amount of up and down motion (up and down force, etc.), and the amount of pitching motion (pitching moment, etc.) of the vehicle, and according to the size of the motion state amount, In step S15, the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels is set. In this case, the distribution ratio of the driver's requested driving force F ^* to the rear wheels 10r may be set to increase stepwise or continuously as the amount of motion state increases. As a result, as the amount of motion state increases, the surplus force of the vertical force of the front wheels 10f increases, and vehicle motion control can be appropriately performed.

In addition, in the present embodiment, when the distribution switching condition is not satisfied, the distribution of the driver's requested driving force F ^* to the front, rear, left, and right wheels is made equal ( S14 ), but it may be made uneven. That is, as long as the vehicle motion control is performed (S13: Yes), the distribution ratio of the driver's requested driving force F ^* to the rear wheels 10r becomes larger than that of the case where the vehicle motion control is not performed (S13: No). It is sufficient to switch the distribution of the driving force required by the driver relative to the front and rear wheels. Of course, the distribution ratio of the driver's requested driving force F ^* to the front and rear wheels set in step S15 is set so that the rear wheels 10r are larger than the front wheels 10f.

(Modification of suspension geometry)

For example, in this embodiment, the conversion ratio (tan(θr)) of the rear suspension 20r is applied to a vehicle in which the conversion ratio (tan(θf)) of the front suspension 20f is larger. A vehicle in which the conversion ratio (tan(θf)) of the wheel suspension 20f is larger than the conversion ratio (tan(θr)) of the rear suspension 20r. In this case, the distribution of the driver's required driving force F ^* to the front and rear wheels may be set so that the front wheels 10f are larger than the rear wheels 10r. Therefore, in the various modified examples described above, the distribution relationship of the driver's requested driving force F ^* to the front and rear wheels may be reversed from that in the embodiment.

Claims (9)

1. A braking and driving force control device for a vehicle, comprising: The actuator independently drives the front, rear, left, and right wheels, and can generate a braking driving force representing both driving force and braking force at each wheel; The suspension link mechanism independently connects the front, rear, left, and right wheels with the vehicle body, and converts the braking driving force of the wheels driven by the actuator into the force in the up and down direction of the vehicle body; The target braking and driving force calculation unit calculates the target braking and driving forces of the four wheels. The target braking and driving forces include the driver's required braking and driving force set based on the driver's operation amount and the vehicle motion control. brake actuation force for motion control; and an actuator control unit, controlling the action of the actuator according to the target braking driving force, in, The suspension link mechanism is configured so that a conversion rate of the braking driving force into a force in the vertical direction of the vehicle body is different between the front wheel side and the rear wheel side, The brake-driving force control device for a vehicle includes a distribution setting unit configured to set a ratio of a wheel connected to a suspension link mechanism on a side with a larger conversion ratio to a smaller ratio of the conversion ratio. The distribution of the driver's required brake-driving force with respect to the front and rear wheels is set in a large manner on one side of the suspension linkage mechanism linking the wheels. 2. The braking-driving force control device for a vehicle according to claim 1, wherein: The brake-driving force control device for a vehicle includes a distribution switching unit configured to control the driver's request in comparison with a case in which the vehicle motion control is not performed when the vehicle motion control is performed. In such a manner that the distribution ratio of the dynamic driving force to the wheels connected to the suspension link mechanism on the side with the larger conversion ratio is large, the distribution of the driver's requested braking driving force to the front and rear wheels is switched, At least when the vehicle motion control is carried out, the allocation setting unit may select the wheel connected to the suspension link mechanism on the side with the higher conversion rate than the wheel on the side with the lower conversion rate. The distribution of the driver's requested braking and driving force to the front and rear wheels is set so that the wheels connected by the suspension link mechanism are large. 3. The braking-driving force control device for a vehicle according to claim 2, wherein: The vehicle braking-driving force control device includes non-sports control allocation setting means for causing the driver to request braking when the vehicle motion control is not being performed. The driving force is equally distributed to the front, rear, left and right wheels. 4. The braking-driving force control device for a vehicle according to claim 2 or 3, wherein: The allocation switching unit is configured to increase the driver's requested brake-driving force relative to the conversion ratio when the yaw motion control of the vehicle is implemented, compared to a case where the yaw motion control of the vehicle is not implemented. The distribution ratio of the wheels linked by the suspension linkage mechanism on one side is large, switching the distribution of the driver's required braking drive force with respect to the front and rear wheels, At least when performing yaw motion control of the vehicle, the distribution setting unit may set the ratio of the wheel connected to the suspension link mechanism on the side with the larger conversion rate to the one with the lower conversion rate. The distribution of the driver's requested braking and driving force to the front and rear wheels is set so that the wheel to which the suspension link mechanism on one side is connected is large. 5. The braking-driving force control device for a vehicle according to claim 1, wherein: The target brake-driving force calculation unit calculates the front wheel roll moment generated by the driving force of the front wheels during the yaw motion control and the rear The brake driving force for motion control of each wheel is calculated in such a way that the rear wheel rolling moment generated by the driving force of each wheel is balanced. 6. The braking-driving force control device for a vehicle according to claim 1, wherein: The braking and driving force control device for a vehicle includes a surplus force equalizing unit configured to allow the braking and driving force of the wheels to generate vertical motion in the vehicle body via the suspension link mechanism. The distribution ratio of the driver's requested braking-driving force to the front and rear wheels is set so that the surplus of force is equal to the front and rear wheels. 7. The braking-driving force control device for a vehicle according to claim 6, wherein: The vehicle brake-driving force control device includes a low-required brake-drive force distribution ratio setting unit, and the low-required brake-drive force distribution ratio setting unit is configured when the driver requested brake-drive force is lower than a predetermined value. In the case of setting the set value, it is set so that the driver's required brake-driving force is distributed only to the wheel connected to the suspension link mechanism on the side with the larger conversion ratio. Distribution ratio of front and rear wheels. 8. The braking and driving force control device for a vehicle according to claim 1, wherein: The vehicle brake-driving force control device includes a state quantity corresponding distribution ratio setting unit that detects a motion state quantity of the vehicle and sets the state quantity corresponding to the state quantity. The ratio of the driver's request for brake-actuation force to the front and rear wheels. 9. The braking-driving force control device for a vehicle according to claim 8, wherein: The state quantity-corresponding distribution ratio setting unit sets such that the distribution ratio of the driver's requested braking-driving force to the rear wheel side increases as the motion state quantity increases.